Technical Abstract: Since Dintzis et al. reported shear-thickening behavior and shear-induced pattern formation in semidilute starch solutions for the first time in 1995, considerable efforts have been made to understand the reason for these behaviors. While the shear-thickening behavior was found to be a breaking procedure of highly concentrated gel-like structures dispersed in dilute starch solutions, the reason for shear-induced pattern formation has not been understood. The pattern formation, observed when the solution is exposed to higher shear rate, is irrelevant to shear-thickening behavior and is not observed below a certain critical threshold shear rate.
In this presentation, we report that the shear-induced pattern formation is caused by the aggregation of starch remnants in the solution. A universal behavior of shear-induced aggregate formation as functions of shear time and shear rate will be demonstrated.